The invention relates to a rotor for an engine, in particular for a gas turbine engine.
A generic rotor as it is for example known from U.S. Pat. No. 5,256,035 has a rotor base part that has fastening grooves for rotor blades that are arranged in succession along a circumferential direction around a rotational axis. At that, the individual rotor blades are supported in a form-fit manner inside corresponding fastening grooves by means of a blade root, respectively. For the purpose of axial securing with respect to the rotational axis, a single-part or multi-part securing element is provided that is supported in a form-fit manner at at least one of the rotor blades at a radially outer edge, and is supported in a form-fit manner at the rotor base part at a radially inner edge.
For example, in U.S. Pat. No. 5,256,035 a multi-part securing element is provided that consists of multiple plate segments and a mounting ring. At that, a radially inner edge of the individual plate segments is received in a form-fit manner inside a groove of the rotor base part, so that a projection of the rotor base part that extends radially outward respectively surrounds the radially inner edge of the plate segments. The mounting ring is in turn received inside a groove that is respectively formed at a blade base of a rotor blade. At that, a projection of the blade base that extends radially inward surrounds the radially outer edge of the mounting ring, thereby also securing a plate segment that is arranged adjacent to and in the axial direction next to the mounting ring.
However, when it comes the individual projections of the multiple rotor blades that are connected to the rotor base part, undesired turbulences may occur in the area of two adjacent projections during operation of the rotor, in particular in the case of a fast-rotating and highly loaded rotor as it is used in a gas turbine engine, for example in the high-pressure compressor or the high-pressure turbine. This is illustrated in more detail in FIGS. 5A, 5B, 5C and 5D, which respectively show sections of a rotor as it is known from the state of the art.
Here, the rotor comprises a rotor base part in the form of a rotor disc 2 with multiple fastening grooves 20 that are arranged at a distance to one another along a circumferential direction U. A blade root 32 of a rotor blade 3a, 3b is received inside each fastening groove 20. Of the plurality of rotor blades that are arranged behind each other along the circumference of the rotor (for example 20 pieces), respectively only two are shown in sections in FIGS. 5A, 5B, 5C and 5D, as viewed along the rotational axis of the rotor. Each rotor blade 3a, 3b has a blade base 31, of which respectively one blade leaf 30 projects radially. In a radially inwardly oriented direction ri, the blade root 32 extends from the blade base 31.
The blade base 31 of a rotor blade 3a or 3b respectively forms a projection 310 that extends radially inwards, i.e. along the inwardly oriented radial direction ri. A radially outer edge 43 of a securing plate 4 is surrounded by this projection 310. Through this securing plate 4, multiple (at least two) rotor blades 3a and 3b are secured at the rotor base part 2 in the axial direction in the area of the fastening grooves 20. For this purpose, the securing plate 4 is connected not only to the rotor blades 3a and 3b, but also to the rotor base part 2. For providing a form-fit connection between the rotor base part 2 and the securing plate 4, a projection of the rotor base part 2, that is not shown in the FIGS. 5A to 5C, surrounds a radially inner edge 42 of the securing plate 4. The longitudinally extending securing plate 4 that extends in the circumferential direction is thus supported at its radially outer edge 43 as well as at the radially inner edge 42, and is respectively received inside a groove that is formed by a rotor blade 3a, 3b or the rotor base part 2.
As can in particular be seen from FIG. 5A, a rotor blade 3a, 3b as it is known from the state of the art respectively forms a projection 310 for surrounding the radially outer edge 43 of the securing plate 4 that is formed over a total length L along the circumferential direction U [by] an edge 311 extending in a continuously linear or circular-arc-shaped manner. Thus, at a pair of rotor blades 3a and 3b that are arranged so as to adjoin each other, their respective projections 310 of adjoining edges 311 should align with each other along the circumferential direction U, so that the radially inner lower edges of these edges 311 lie on a circular orbit around the rotational axis M of the rotor.
However, as is illustrated in FIGS. 5B and 5C, that is actually often not the case in practice. Thus, due to the tolerances to be admitted, it may occur that the individual projections 310 of adjacent rotor blades 3a, 3b are radially offset with respect to one another. Here, FIGS. 5B and 5C respectively show an offset g of the two rotor blades 3a and 3b in the area of their projections 310 in an exemplary manner. At that, in the variant of FIG. 5B, the one (left) rotor blade 3b is offset radially inward with respect to the adjacent (right) rotor blade 3a. The one projection 310 of the one rotor blade 3b thus protrudes into the annular gap flow in the circumferential direction U (offset “into wind”) with respect to a rotational axis of the rotor about the rotational axis M along the circumferential direction. In the variant of FIG. 5C, the one (left) rotor blade 3b is offset radially outward with respect to the other (right) rotor blade 3a (offset “out of wind”). The edge 311 of the projection 310 of the one rotor blade 3b is thus completely offset radially outward with respect to the projection 310 of the other rotor blade 3a. 
Although it is observed in practice that an offset g for both cases lies only in the range of 0.2 mm to 0.4 mm in a rotor, undesired turbulences may occur here in the area of adjoining blade bases 31 and thus in adjoining projections 310, especially in fast-spinning rotors for a gas turbine engine, for example in a rotor of a high-pressure turbine or a high-pressure compressor.